Whenever you make any changes to your application, they are not applied immediately right after you make them. They are first all recorded in the changelog, and are applied only when you want to. Doing so is a straight forward process in your backend, and can be done with only a few clicks. Simply click the green Update the project button in the top right of your screen and then click Update now.
All the changes that you have made will then be made live on your app for your users to see.